Reactions Involving Two-co-ordinate Phosphorus

5-dioxo-l,3,2-dioxaphospholane (128) has been prepared and subjected to thermal or MS fragmentation an intense peak corresponding to (129) was found in the El mass spectrum, and thermolysis gave (130), both results in accordance with a facile formation of the arylphosphinidene oxide (129) from (128). Pyrolysis of the cyclic phosphites (131) gave a deposit on a — 195°C cold finger which according to P NMR contained some aryl phosphenite (132), the chemistry of which could be studied for the first time. A full paper has appeared on the preparation and properties of the stable ylidylphosphinidene chalcogenides (133).  

The iminophosphine (134) with 1-alkynes gave various products of 1,1- or 1,2-additions. A new synthesis of diphosphenes (135) from aryldichlorophosphines and a tungsten complex has been described the tungsten complex catalysed an exchange between two diphosphenes to give the unsymmetric diphosphene. A ferrocenyl-substituted diphosphene (136) has been prepared which seems to represent a borderline case with respect to dimerisation thus the dimer (137) readily dissociates to (136) upon heating in xylene. 

The first example of a phosphenium ion (138) with a P-C single bond has been prepared and characterised by X-ray crystallography. An X-ray structural study of the phosphenium tetraphenylborate (139) showed a phosphenium ion without cation-anion interactions. 

Phosphoryl chloride (107) has been prepared in a high temperature reaction between phosphoroxychloride and silver, and characterized by m.s. and i.r. spectroscopy. Ab initio calculations on the simplest x -iminophosphine, (108), indicate a tranir-planar structure, although the cis isomer is only 0.6 kcal mol higher in energy.  

Binnewies, M. Lakenbrink, and H. Schndckel, Z. Anorg. Allg. Chem., 1983, 497, 7. 

Cycloaddition reactions of two-co-ordinate phosphorus compounds described this year includes the [2 + 2] cycloaddition of an iminoborane to aminoimino-phosphines to give 1,3,2,4-diazaphosphaboretidines (125). In an attempt to prepare hydrazino-bis-phosphaalkenes (126) as new candidates for hetero-Cope rearrangements, the tricyclic compounds (127) were obtained. The result is explained by a Diels-Alder rearrangement of (126), as shown. 

Phosphenium ions (135) react with phenyl azide in a Staudinger reaction to give the novel diaminoiminophosphenium ions (136). Some papers have appeared this year on diphosphenes after the discovery of the first stable diphos-phene (137) last year. New diphosphenes, which were all synthesized from 

Walker, in Organophosphorus Chemistry , ed. D. W. Hutchinson and B. J. Walker (Specialist Periodical Reports), The Royal Society of Chemistry, London, 1983, Vol. 14, 

---

The organization of this Chapter has been changed somewhat from last year. Phosphonous and phosphinous acids and their derivatives, and cyclic esters of phosphorous acid, are not discussed separately from phosphorous acid and its derivatives, because of the similarity of the reactions involved. Two-co-ordinate phosphorus compounds are treated in a separate section like last year phospha-alkenes without phosphorus-heteroatom bonds are not covered. 

---